Project Summary/Abstract Atrial fibrillation is the most common disorder of the heart rhythm that requires treatment, with a prevalence estimated at over 5 million in the US alone in the year 2000. If untreated, it is associated with increased risk of death and disability, primarily due to stroke. There is increasing evidence that a significant percentage of atrial fibrillation goes undetected, because it either does not immediately cause symptoms, or is episodic, and not present in the brief periods that the electrocardiogram is monitored, which are typically for minutes up to two days. [unreadable] [unreadable] Technology developed at the University of Washington allows convenient and accurate monitoring of the electrocardiogram in patients outside of the hospital for prolonged periods, up to at least four weeks. The device weighs less than an ounce, and uses built-in intelligence to classify the recorded tracings, looking for atrial fibrillation. [unreadable] [unreadable] This project will have two goals. The first is to directly compare the techniques used in this device to other published techniques, using a previously annotated and classified set of recorded, long-term ECGs. The second is to use the device on subjects with atrial fibrillation undergoing standard 24 or 48 hour monitoring, to compare the yield of atrial fibrillation, and accuracy of determination of duration of atrial fibrillation. PUBLIC HEALTH RELEVANCE Atrial fibrillation is the most common rhythm disorder of the heart which can cause disability or death, and it affects millions of individuals in the United States. Individuals may have atrial fibrillation without being aware of it. This project will further develop a technology which can inexpensively and comfortably identify subjects with intermittent atrial fibrillation but do not experience any symptoms, allowing them to be treated to reduce their risk. [unreadable] [unreadable] [unreadable]